Method and Apparatus for Underwater Dredging

ABSTRACT

An encapsulated underwater dredge assembly is operable at depths up to 1,200 feet or more. The underwater dredge assembly has multiple cutting assemblies, beneficially disposed around a centrally positioned dredge pump; each of the cutting assemblies can rotate in clockwise or counterclockwise directions, as desired. All components of the dredge assembly are hydraulically powered and operated.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention pertains to a method and apparatus for performing underwater dredging. More particularly, the present invention pertains to a dredge assembly employed to excavate and remove solid matter (including, without limitation, earth) from below the surface of a body of water.

2. Brief Description of the Prior Art

It is frequently beneficial to clean out the bed of a body of water by scooping out mud, vegetation, rubbish and/or other debris using a dredge assembly. Although the applications for dredging are too numerous to list, dredging is frequently employed in connection with the offshore oil and gas industry and/or operations in support thereof. However, conventional underwater dredging operations typically suffer from a number of important limitations including, without limitation, depth, speed, dredge stability and overall effectiveness.

Conventional dredging equipment generally includes a barge which floats on the surface of a body of water and supports an elongated downwardly extending boom having a dredging tool at its distal end. The dredging tool may include a rotary head or other cutting implement, and is typically operated using power supplied from said barge. Such conventional dredging tools generally do not remove solid materials evenly and cannot be used below certain depths. Moreover, it is frequently difficult to effectively control movement of such underwater dredging tools.

Thus, there is a need for an effective dredging tool that can efficiently remove earth, mud, debris and other materials from an underwater environment. Such dredging tool should be capable or working at greater depths, should be easier to control, and should be more effective than conventional dredging tools.

SUMMARY OF THE INVENTION

The present invention comprises an encapsulated underwater dredge assembly operable at depths up to 1,200 feet or more. In a preferred embodiment, the subsea dredge assembly of the present invention comprises a plurality of cutting assemblies beneficially disposed around a centrally positioned centrifugal dredge pump.

All components of the dredge assembly of the present invention are hydraulically powered and operated. In addition to operating said centrifugal dredge pump, the hydraulic system of the present invention can also operate said dredge excavators or cutter assemblies. All of said components receive hydraulic flow from a central hydraulic input source eliminating the need for extra hoses to the dredge cutter hydraulic motors. Said hydraulic system is fully enclosed, preventing diesel and hydraulic spillage.

Each dredge cutter assembly can rotate either in a clockwise or counterclockwise direction, as desired, and beneficially directs cuttings into said centrifugal pump and makes a flat cut pattern. Blades of said dredge cutter assemblies are changeable, and replaceable with re-dressed or re-configured blades. The subsea dredge assembly of the present invention can also include externally mounted emergency shut down and engine controls.

In addition to said subsea dredge assembly, the hydraulic system of the present invention can operate virtually any hydraulic tool. Further, said hydraulic system of the present invention provides a flow-rate up to 250 gallons per minute and pressures up to 5,000 PSI. This hydraulic system can operate hydraulic motors and hydraulic cylinders; hydraulic control valves can simultaneously be manually operated, or operated using an electronic radio control system.

Features of a preferred embodiment of the subsea dredge assembly of the present invention include the following:

The operating system of the present invention can be installed in a modified steel container that is 8 feet wide by 20 feet long with a rear door double door, a side door, and louvers in front and side to vent air into and exhaust air out of said container.

The diesel engine is 800 horsepower unit with a triple pump drive mounted on the power takeoff. The triple pump drive has 2-hydraulic actuated clutches mounted into the drive plate and one drive plate without a clutch. Each clutch drive operates a 130-gallon per minute pressure compensated piston pump for a total combined flow of 260 gallons per minute from 2-pumps. The pump drive without a clutch operates 80 gallons per minute pressure compensated piston pump. Mounted on the backside of this pump is 50 gallons per minute gear pump.

The 80 gallons per minute pressure compensated piston pump is connected to a proportional directional valve that is mounted on an external hose reel that operates that operates the reel in paying out and paying in by using a radio control system operated by a technician that can be in the line of sight of the dredge operator.

The 260 gallons per minute combined flow that comes from the two pressure compensated piston pumps go out to the hose reel through a rotating union and is coiled onto a hose reel drum with a line capacity of 1,200 feet. The hose has a 2-inch inside diameter and there are two hoses and a third hose with a 1½ inch inside diameter bundled together and wrapped around hose reel drum. The hose reel has a level wind that lays down the hose bundle in a uniform manner. All three hoses are connected to a dredge unit that consists of a centrifugal pump driven by a bent axes hydraulic motor and a plurality of surrounding hydraulic operated excavators.

The gear pump that is mounted on the back side of the 80 gallons per minute pressure compensated piston pump operates the two hydraulic clutches and is used to continuously filter the hydraulic oil in the hydraulic reservoir while the oil is passing through a heat exchanger.

All hydraulic oil is contained in 550 gallon steel reservoir with visual level indication; a low level shut down in the event leakage when the oil level is down to an unsafe level. Filters are mounted on top of the reservoir to prevent oil spillage when changing filter elements. The diesel reservoir is contained in a 350 gallon steel reservoir with visual level indication and is plumbed through a line filter and then to the diesel engine. The electrical system starting the diesel engine and operation all electrical controls that operated the diesel engine, hydraulic system and radio controls use 24-volt DC.

BRIEF DESCRIPTION OF DRAWINGS/FIGURES

The foregoing summary, as well as any detailed description of the preferred embodiments, is better understood when read in conjunction with the drawings and figures contained herein. For the purpose of illustrating the invention, the drawings and figures show certain preferred embodiments. It is understood, however, that the invention is not limited to the specific methods and devices disclosed in such drawings or figures.

FIG. 1 depicts a side view of a dredge assembly of the present invention being deployed from a floating vessel.

FIG. 2 depicts a partial cut-away side view of a dredge assembly of the present invention.

DETAILED DESCRIPTION OF A PREFERRED EMBODIMENT

Referring to the drawings, FIG. 1 depicts a side view of a dredge assembly 100 of the present invention being deployed from a floating vessel 200. As depicted in FIG. 1, floating vessel 200 is deployed at surface 300 of a body of water. Said dredge assembly 100 is suspended from boom 210 of vessel 200, and is deployed at water bottom 400. Conduit 110 extends from vessel 200 to underwater dredge assembly 100.

FIG. 2 depicts a partial cut-away side view of dredge assembly 100 of the present invention. In the preferred embodiment, subsea dredge assembly 100 of the present invention comprises a central support frame 101 supporting central pump 130. Although other types and configurations of pumps can be used, in a preferred embodiment pump 130 comprises a centrifugal pump having a substantially downwardly facing pump intake 131. Pump 130 has pump discharge outlet 132 that can be connected to conduit 110 (depicted in FIG. 1) for transportation of earth, vegetation, debris or other materials to water surface 300.

A plurality of cutting assemblies 120 are beneficially disposed around centrally disposed dredge pump 130. Said cutting assemblies 120 are securely mounted to support frame 101 using mounting arms 140, while said mounting arms 140 extend radially outward at an acute angle from support frame 101 in a partially downwardly direction. Although other numbers of cutting assemblies 120 can be employed without departing from the scope of the invention, in a preferred embodiment four (4) cutting assemblies 120 are disposed around central pump 13 and are equidistantly spaced apart.

Each cutting assembly 120 comprises a motor 121 having a central rotating spindle 123. Cutting elements 122 are disposed on said spindle 123. In operation, motor 121 powers rotation of spindle 123 which, in turn, drives rotation of cutting elements 122. Blades 122 of said dredge cutting assemblies 120 are changeable, and replaceable with re-dressed or re-configured blades.

When placed in contact with an underwater mudline (such as, for example, water bottom 400), cutting elements 122 act to mechanically cut, break up or loosen such earth or other solid material. Such earth or other solid material is directed toward intake 131 of pump 130, and is pumped via conduit 110 (depicted in FIG. 1) to water surface 300.

Each cutting blade 122 is capable of rotating about an axis passing through a spindle 123 in either a clockwise or counterclockwise direction, as desired. In a preferred embodiment, opposing pairs of cutting blades (that is, cutting blades that are positioned directly across—or 180 degrees—from each other on either side of pump 130) rotate in opposite directions from one another; as such, when a first cutting blade 122 rotates in a clockwise direction, a second cutting blade 122 positioned directly opposite from said first cutting blade 122 rotates in a counterclockwise direction. In this manner, dredge assembly 100 remains evenly balanced (rather than leaning to one side or the other) while making a substantially flat cut pattern. Further, operation of said opposing pairs of cutting assemblies 120 can be linked, so that if one cutting assembly of a pair ceases operation for any reason the opposing cutting assembly of said pair can also cease operation to further promote event cutting and prevent unwanted twisting or torque forces acting on conduit 110 (see FIG. 1)

All components of dredge assembly 100 of the present invention are hydraulically powered and operated. In addition to operating centrifugal dredge pump 130, the hydraulic system of the present invention can also operate cutting assemblies 120. All of said components receive hydraulic fluid flow from a central hydraulic input source eliminating the need for extra hoses to hydraulic cutting assembly motors 121. Said hydraulic system is fully enclosed, preventing spillage of diesel fuel and hydraulic fluid.

In addition to said subsea dredge assembly, the hydraulic system of the present invention can operate virtually any hydraulic tool. Further, said hydraulic system of the present invention provides a flow-rate up to 250 gallons per minute and pressures up to 5,000 PSI, and can also operate hydraulic motors and hydraulic cylinders; hydraulic control valves can simultaneously be manually operated, or operated using an electronic radio control system.

The operating system of the present invention can be installed in a modified steel container (for example, a standard container that is approximately 8 feet wide by 20 feet long) with a rear door double door, a side door, and louver vents in front and side to vent air into and exhaust air out of said container. Further, said hydraulic system can include a reeled hydraulic hose that can provide for paying out and paying in using a radio control system. Although not required, said reel system can be operated by an operator that can be in the line of sight of the dredge operator. Said hose reel can further comprise a level wind that lays down the hose bundle in a uniform manner.

Hydraulic fluid is continuously filtered in the hydraulic reservoir while hydraulic fluid passes through a heat exchanger to cool such hydraulic fluid. All hydraulic fluid can be contained within a steel reservoir with visual level indication; a low level shut down in the event of leakage or when such fluid reaches an unsafe level. Filters are mounted on top of the reservoir to prevent oil spillage when changing filter elements. Similarly, a diesel reservoir is contained in a steel reservoir with visual level indication and is plumbed through a line filter and then to a diesel engine. The subsea dredge assembly of the present invention can include externally mounted emergency shut down and engine controls.

The above-described invention has a number of particular features that should preferably be employed in combination, although each is useful separately without departure from the scope of the invention. While the preferred embodiment of the present invention is shown and described herein, it will be understood that the invention may be embodied otherwise than herein specifically illustrated or described, and that certain changes in form and arrangement of parts and the specific manner of practicing the invention may be made within the underlying idea or principles of the invention. 

What is claimed:
 1. A dredging assembly comprising: a) a plurality of cutting assemblies; and b) a dredge pump centrally disposed between said cutting assemblies.
 2. The dredging assembly of claim 1, wherein said cutting assemblies comprise: a) a motor having a central drive shaft; and b) at least one cutting blade attached to said drive shaft.
 3. The dredging assembly of claim 2, wherein said motor and dredge pump are hydraulically operated.
 4. A dredging assembly comprising: a) four cutting assemblies; and b) a dredge pump centrally disposed between said cutting assemblies, wherein said cutting assemblies are equidistantly spaced around said dredge pump.
 5. The dredging assembly of claim 4, wherein said cutting assemblies comprise: a) a motor having a central drive shaft; and b) at least one cutting blade attached to said drive shaft.
 6. The dredging assembly of claim 5, wherein said motor and dredge pump are hydraulically operated. 